It's the National Holiday. It was celebrated the first time in 1990 when the official reunion of the German Democratic Republic and the Federal Republic of Germany took place. Each year on 3rd of October people celebrate the unified Germany; the day is also a reminder for younger people that Germany wasn't always just one country.
In Germany and Austria it is the 1st Sunday in October.
It's celebrated on October 3rd
you
they like to celebrate with mettwurst
no
nothing
no
If they are Christians, you don't need to be a certain nationality to celebrate lent.
December 24.
DECEMBER 24
Feb. 2nd
Oktoberfest is essentially a beer drinking festival in a convivial atmosphere. About the only difference would be that Germans celebrate it in Germany and Australians celebrate it in Australia with fake German accents.